Related Stories

Dragonflies are among the most ancient of insects — they were darting across rivers and lakes long before dinosaurs appeared — and have evolved many mechanisms to survive, says Dr Dan Bickel, an entomologist with the Australian Museum.

Powerful eyes and impressive flying abilities are chief among their abilities, says Bickel.

"They can fly further, higher and faster than most insects, sometimes at speeds of up to 70km per hour."

Dragonflies are able to propel themselves upwards and downwards, backwards and forwards, side to side and hover in midair.

And many of these flying abilities are thanks to the insect's distinctive wings.

The dragonfly has two sets of wings — one behind the other — that can be used in tandem or independently.

Running through each wing is a network of veins that adds strength and flexibility. This allows the dragonfly to curve and cut through the air, Bickel says.

"It's a very dynamic sort of system — it's very lightweight, flexible and strong."

This vein structure is held together by a very thin, shiny film made from chitin (pronounced kite-en); a starch variation that makes up the exoskeletons of most insects.

A great number of invertebrates — including prawns, spiders and insects — have exo or external skeletons; meaning that unlike humans they are "soft on the inside, hard on the outside," Bickel says.

Chitin, says Bickel, is not elastic so that when the animal wants to grow, it has to push out of its wings, split open the structure and wait for a new exoskeleton to harden. The most well known example of this is the cicada pushing out of its shell.

Bickel says the wings are "really smooth, with no bumps" which makes the chitin appear glassy and reflective.

Ken Walker, insect curator with Museum Victoria says chitin in its natural form is translucent and it's the "extreme thinness" of dragonfly wings that make them appear glassy.

This shininess is not exclusive to dragonflies.

"There are a lot of other insects with the glassy wing — flies, bees, wasps. Many of them have the same transparent, glassy, chitinous structure," says Walker.

Bickel says if you were to remove the colourful scales from a butterfly, their wings would be glassy too.

Also, not all dragonfly wings appear glassy. With some 6,000 species worldwide — 320 of which are found in Australia — there is a great variety to how their wings look.

"Some are transparent while others are brightly coloured, reddish, brown or even metallic," Bickel says.

"Those which lack pigment look more pure and glassy."

The different wing patterns and colours probably allow the insects to attract and recognise desired mates within their own species.

Nor is the wing appearance uniform over the course of a dragonfly's lifespan, with the colour often dulling as the insect matures.

Dr Dan Bickel, is an entomologist with the Australian Museum; and Dr Ken Walker is Senior Curator of Entomology and Arachnology at Museum Victoria. They were interviewed by Katie Silver.